As technology continues to progress and more and more electronic devices become increasingly common in all industries, the focus on Electromagnetic Interference (EMI) becomes immensely important. Electromagnetic Interference, also known as radio-frequency interference (RFI), is a disturbance that may affect an electrical circuit due to either the electromagnetic induction or radiation emitted from an external source. The external source may be either artificial or natural, making this an extremely hard problem to resolve due to the large amount of variance that the EMI could be sourced from. Devices such as cell phones, tablets, and computers are some of the main emitters of EMI. Electronics such as these could eventually lead to the disruption, degrading, or interruption of the performance of circuits, render them useless, or destroy them completely through interference overload. Every electronic device emits a type of EMI that can be potentially harmful. Thus, the reason for why this problem must be addressed with new technology.
Any electrical or electronic device has the potential to generate conducted and radiated interference. Typical sources of conducted interference may include switching power supplies, alternating current (AC) motors, microwave ovens and microprocessors.
EMI generates unwanted signals from a first circuit, (e.g., a radio, computer chip, computer board, and the like), that may be picked up by a second circuit. This may cause the second circuit to operate less efficiently than desired. In the simplest cases, the second circuit may have “glitches” in its operations, although this may extend to the second circuit yielding incorrect data.
Typically, EMI has been contained at the “box” level of a device, (as dictated by government health and environmental safety regulations), or at best with grounded shielding around a specific component or set of components. In its most extreme form, (i.e., high security/cryptographic environments), the entire device may be enclosed within a shielded room.
Despite there being many types of absorbers, all work through a process of converting unwanted electrical and magnetic emissions into small amounts of heat. The “absorption” strategy is one of attenuation and differs with “shielding” which may be viewed as a strategy of isolation, in that it utilizes conductive material to contain EMI by reflecting the unwanted emissions back towards their source.
Some of the metalized products used by the electronics industry to shield and contain EMI include; metalized gaskets, conductive coatings, shielding tapes, finger stock and an array of ferrite products including beads, toroids, chokes and inductors.
It is quickly becoming apparent that as clock speeds continue to increase, the frequencies emitted will also climb. This will make EMI management an ever-increasing problem. Traditional shielding methods such as finger stock, fabric-over-foam, and board-level shields will prove to be increasingly less effective in these environments. Ironically, it is often these traditional materials that contribute to the resonance problem. They provide a conductive path for energy, which in turn keeps the energy inside the cavity. This contained energy may adversely affect other components on the board and may keep the board from functioning properly. Apart from containment related problems, traditional reflective type shielding technologies simply can no longer hold the waveform . . . it is simply too small at these higher frequencies.
The damaging effects of electromagnetic interference may pose unacceptable risks in many areas of technology, and it is desirable to control such interference and reduce the risks to acceptable levels.